Genetics And Utilization Of Noval Wheat-Agropyorn Cristatum Germplasm With Multi-Kernel

Grain number per spike (GNPS) is one of the three factors of wheat yield. High GNPS germplasm iskey genetic resources with high yielding potential. Pubing3504derived from progeny of the crossbetween common wheat and Agropyron cristatum (L.) Gaertn, showed prominent GNPS. In this study,by investigating the ecological stability of Pubing3504in different wheat ecological regions andanalyzing genetic effect of high GNPS under different wheat background, uncovering major QTLs andthe genomic regions of GNPS and yield-related traits, comparing differentially expressed genes andproteins of young panicle in Pubing3504, the genetic nature of high GNPS in Pubing3504wereexplained.1. The ecological adaptation was evaluated. Pubing3504were grown in five ecological areasincluding Beijing, Yangling in Shaanxi, Chengdou in Sichuan, Nanjing in Jiangsu and Shijiazhuang inHebei in2006-2007and2007-2008growth seasons and investigated GNPS. The results indicated thatPubing3504showed high GNPS in all ecological areas and the GNPS range from82.7to145with anaverage value of102.66, which was significant higher than control (41.7-63.26). The results indicatedthat Pubing3504had a stable and wide adaptability to different ecological regions.2. The genetic effect of GNPS under different genetic background was analyzed. An incompletediallel cross design was explored using Pubing3504as a common parent crossed with nine wheatvarieties (high GNPS level>52, mid GNPS level40-52, low GNPS level <40). The GNPS of F1hybridsand F2populations were investigated in Beijing, Sichuan and Shaanxi in2008-2009,2009-2010and2010-2011growth seasons, respectively. The results showed that the average relative increase ratio ofGNPS in populations was46.07%. Genetic analysis by QGAStation1.0software suggested that GNPSwas mainly controlled by additive genetic effects, and the average narrow-sense heritability was31.16%.Genetic variation coefficient was25.19%; and the genetic advance (selection response) under5%and1%selection intensity was27.86%and36.25%, respectively. The relative genetic advance was44.20%and57.53%, respectively. And additive effect of Pubing3504was the highest in parents with the value of27.417. In the same cross, the breeding effect of Pubing3504as the male parent was superior to itself asthe female parent. Correlation between GNPS and thousand grain weight (TGW) of F2populations waslow (R2=0.0024). The results showed that more individuals with both high GNPS and high TGW couldbe readily screened out from F2segregation populations using Pubing3504as parent.3. The F2:3population was developed from the cross between Pubing3504and Jing4839, and theseven yield traits including GNPS, spike length (SL), kernel number per spikelet (KPS), spikelet numberper spike (SNS), TGW, spike number per plant (SNP), plant height (PH) from F2population in Beijing(2008-2009) and F3family lines in Beijing, Sichuan, Shaanxi (2009-2010) were investigated,respectively. The results showed that the broad-sense heritability of all traits were up to70%. Correlationanalysis indicated that the significant positive correlations between GNPS and spike component factorsincluding KPS, SNS and SL, especially KPS (R2=0.2809-0.7225). While GNPS had insignificant correlation with TGW and weak correlation with SNP (R2=0.1521-0.3721).4. The genetic linkage map was constructed. A total of190SSR, EST-SSR and STS molecularmarkers were used to genotype the282individuals of F2population.The genetic map involving all thewheat chromosomes except2B, covered the genetic distance of3171.60cM with an average markerinterval of16.69cM.5. Based on the constructed genetic map, the QTL analysis by Network2.0for the yield traits wasconducted. As a result, a total of37QTLs (in a single environment) and25QTLs (in joint environment)were identified. A major QTL QGnps.cd-1A, were detected by four environments and explained13.01%-64.47%of the phenotypic variation. QKps.cd-1A.1, QSns.cd-1A and QSl.cd-2D were threemajor QTLs controlling KPS, SNS and SL, respectively. Among them, QKps.cd-1A.1and QSns.cd-1Awere in the same site with QGnps.cd-1A. Conditional QTL analysis showed that QGnps.cd-1A was apleiotropic QTL with GNPS, KPS and SNS. In addition, major QTL QSnp.cd-1A controlling SNP wasdetected, major QTLs including QTgw.cd-4B and QHt.cd-4B were detected, which controlled TGW andHT, respectively. The interaction of QTL×environment were detected with GNPS, KPS, SL, SNP andHT in joint environment analysis, and the contribution rate from QTL×environment interaction was0.21%-7.89%. Additive effects of70.3%(in a single environment) and57.6%(in joint environment)QTLs were positive contributed by Pubing3504alleles.6. QTL mapping results show that five important genomic regions on chromosomes1A,4A,4B,2D and4D were detected. Among them, the marker interval Xmag834-Xbarc83on the short arm ofchromosome1A was a novel important genomic region, which included the QTLs that controlled GNPS,KPS, SNS, TGW and SNP with good environmental repeatability. All these QTLs were major QTLsexcepting the TGW and all these QTLs additive effects came from Pubing3504excepting the SNP. Theregions showed the same genetic characteristics as founder parents and might play a very key role inimproving wheat yield in future.7. Fragments of P genome in Pubing3504were detected and tracked. There were3362P genomespecific markers in common wheat Fukuho background were used to identify alien P chromosome in"Pubing3504". The results showed that two markers could be detected in "Pubing3504", and mappingedon3A and4A chromosomes, respectively.8. Gene and protein expression profiling analysis were carried out. Compared to the control parentFukuho, the gene and protein expression profiling were studied in young spike of high GNPS wheatgermplasm (Pubing3504, Pubing3228and4844-12) using Affymetrix wheat chip and iTRAQ-MS/MStechnology. There were611transcripts (272up-regulated and339down-regulated transcripts) and282proteins (123up-regulated and159down-regulated proteins) expressed differentially in high GNPSgermplasm totally. Among them, flowering repressor GASA5, ZCCT2, ZCCT1were up-regulated, andflowering promotive factor FCA was down-regulated, implying that the conversion of the SAM into thefloral meristem was delayed, which was beneficial to forming more spikelets; Meanwhile, protein kinasewith AP2domain and HUA2were up-regulated, implying that expression of genes controlling thenumbers of floral organs were enhanced, which were beneficial to the floret formation in high GNPS germplasm. Both of the two reasons above might involve the formation of high GNPS characteristics.Furthermore, the143pairs P genome-special STS markers and132pairs the STS markers of wheatrelated to high GNPS were developed by differentially expressed EST sequences in genechips and fiveof them were mapped on1A,3A,6A and7B chromosomes, respectively.